Rabies, HIV, Hepatitis, Tetanus can all be spread through bites, animal or human. There are of course insect bites that will give you all kinds of diseases: yellow fever, dengue fever, Lyme disease, plague, malaria, etc. But I’ll focus on Rabies, for now.
The discovery of the cause of rabies didn’t occur until the early 1800’s and didn’t get a vaccine until Louis Pasteur figured things out later that century.
I have to wonder about the disease, Lyssavirus (named after Lyssa, the Greek goddess of insanity and rage) and its symptoms, in one variant, madness and an odd psychological fear called hydrophobia.
So, you, a carrier, bite someone and your victim becomes infected, insane with madness, and cringes from the sight of some mundane substance. Sound familiar?
(Seems that Lyssa and Lycaon, the Greek king who was cursed by Zeus to become the first werewolf, could have made the perfect couple.)
Hey, Bram Stoker, did you read about rabies in the London libraries around the 1890’s? Two legends, vampires and werewolves, both being vectored by saliva (viral infection) passed during a bite. Hmm, a curious coincidence.